1. Field of the Invention
The present invention relates to a spatial light modulator which comprises a photoconductive member and a photo-modulation member and is adapted to be used in an optical information processing device for parallel processing of moving images or still images or for displaying or storing thereof and, particularly, to an improvement thereof of the photoconductive member of the spatial light modulator.
2. Description of the Related Art
As an example of a spatial light modulator to be used in image processing, a liquid crystal light-valve element is disclosed in Japanese Patent Laid-Open No. 58-199327(1983). The purpose of the liquid crystal light-valve element in this patent application is to obtain a high resistance, high sensitivity photoconductive member, and the liquid crystal light-valve is composed of an amorphous silicon layer, a light-blocking layer and a liquid crystal layer arranged in the order. The amorphous silicon layer corresponding to the photoconductive member is doped with boron at any density selected from a range from 10 ppm to 400 ppm considering a variation of the Fermi level thereof.
In such a conventional technique, however, an application of drive voltage to the liquid crystal layer tends to be delayed since response speed of the amorphous silicon layer itself to light is not always high enough.
Therefore, although the above mentioned conventional light-valve may be used in a defect test device as described, it can not guarantee high image quality for a display of a moving image due to the so-called after-image problem.